ATHENS, Ga., Oct. 29 (UPI) -- U.S. scientists have created a vaccine that in an animal study successfully generated protection against cancer cells.

The researchers at the University of Georgia Cancer Center synthesized a carbohydrate-based vaccine that -- in mice -- successfully triggered a strong immune response to cancer cells.

"In mice we can illicit very strong antibody responses and we have shown that the antibody responses are functional -- that they can kill cancer cells," said Professor Geert-Jan Boons, lead author of the student.

Vaccines usually prevent diseases by priming the immune system to recognize and attack a virus or bacteria. But the vaccine Boons and colleagues developed is a therapeutic vaccine that trains the body's immune system to fight an existing disease.

"We needed to come up with a vaccine that does not give our immune system a chance to go after anything else but the tumor-associated carbohydrate," Boons said. "In other words, there should no junk that can induce an immune response to something other than the tumor-associated carbohydrate."

The research is reported in the journal Nature Chemical Biology.

Melting ice prompts navigation warning

BOULDER, Colo., Oct. 29 (UPI) -- The U.S.-based International Ice Charting Working Group predicted significant navigation hazards will develop as Arctic sea ice diminishes.

The statement was released during a conference last week at the European Space Agency's Earth Observation Center in Frascati, Italy.

At the end of September, satellites indicated the Arctic sea ice was at its lowest extent in the history of ice charting. "The International Ice Charting Working Group cautions that sea ice and icebergs will continue to present significant hazards to navigation for the foreseeable future," the scientists said in a statement.

During the last 25 years, satellites observed the minimum Arctic ice coverage at the end of summer decreased from around 3 million square miles during the early 1980s to less than 1.6 million square miles as observed in September.

That reduction in sea ice has occurred much more quickly than global climate models predicted.

"The overall extent was similar to what some of the models envisioned but decades in advance of when they expected that would occur," said Douglas Bancroft, director of the Canadian Ice Service. "In fact, the summer of 2007 looked very similar to some climate model forecasts for 2030 to 2050."

New causes of neurodegeneration are found

ANN ARBOR, Mich., Oct. 29 (UPI) -- U.S. scientists have found a link between a virtually unknown signaling molecule and neuron health that affects such diseases as Alzheimer's.

University of Michigan researchers led by graduate student Yanling Zhang, postdoctoral fellow Sergey Zolov and Professor Lois Weisman connected the loss of the molecule to massive neurodegeneration in the brain.

The molecule PI(3,5)P2 is a lipid found in all cells at very low levels. While the best-studied lipids are fats, waxes and oils, PI(3,5)P2 is a member of a unique class of lipids that signal the cell to perform special tasks.

Weisman said it was surprising to find PI(3,5)P2 plays a key role in the survival of nervous system cells.

"In mice, lowered levels of PI(3,5)P2 leads to profound neurodegeneration," said Weisman, which he said suggests it is a good place to look to find treatments for neurodegenerative diseases such as Alzheimer's and multiple sclerosis.

The study is reported in the Proceedings of the National Academy of Sciences.

Origin of Earth's atmosphere discovered

COLUMBUS, Ohio, Oct. 29 (UPI) -- U.S. researchers have discovered what might be evidence of the origin of Earth's breathable atmosphere, similar to the planet's current oxygen-rich air.

Ohio State University geologists and colleagues said the study suggested upheavals in the Earth's crust initiated a kind of reverse-greenhouse effect 500 million years ago, cooling the world's oceans, spawning giant plankton blooms and sending a giant burst of oxygen into the atmosphere.

Associate Professor Matthew Saltzman, who led the study, said that oxygen might have helped trigger one of the largest growths of biodiversity in Earth's history.

The findings were reported Sunday in Denver during the annual meeting of the Geological Society of America.